1. Field of the Disclosure
The present disclosure relates to methods of document creation. More specifically, the present disclosure is directed to an apparatus and method for printing in which the media flatness is verified before printing in a preview mode and/or during printing.
2. Brief Discussion of Related Art
In certain printers using ink jet direct marking technology, it is expected that marking inks, e.g., solid inks, UV gel inks, aqueous inks and others, will be jetted directly onto cut sheet substrate media. A critical parameter in this printing process is the size of the printhead-to-media gap. In certain current technology, the gap is set as small as 0.5 mm in order to minimize the pixel placement errors due to misdirected jets. For other printheads, for example those having high drop velocity, it is possible that the gap can be opened to 0.75-1.0 mm. Nevertheless, these tight printhead to media gaps pose a challenge for any cut sheet printer, since the sheet lead edge (LE) and trail edge (TE), and to a less extent the sheet body are generally not perfectly flat.
For accurate pixel placement and color registration, it is desired to keep the printhead-to-media gap within a +/−0.1 mm range about the nominal. To avoid printhead front face damage, under no circumstances is the media allowed to “close the gap”, i.e., to contact the printhead. Both vacuum and/or electrostatic escort belt technology are employed to hold cut sheets of substrate media sufficiently flat. However, neither technology is robust against LE & TE upcurl.
On solution to the problem of upcurl is that a cut sheet printer may have a precurler subsystem which biases all sheets into a downcurl mode. However, if an operator places a stack in the feed tray with non-uniform curl, such as edge wave, corner curl, or cockle, it will be difficult for the precurler to produce sufficient downcurl from the very first sheet of a job. Hence, sheets may not be held sufficiently flat in the print zone, to the extent that a shutdown of the printer would be necessary to avoid the uncurled media contacting the printheads.